Implement almost functions

- Auto-cache explanations of word
- Allow to cache words through specifing a word list file manually
- Add config file
- Provide a word list that I just use at `doc/word-list.txt'

README.rst

@@ -10,8 +10,9 @@ Usage
 
 .. code-block:: text
 
-   usage: ldcv.py [-h] [-f] [--color {always,auto,never}] [-j]
-                  [words [words ...]]
+   usage: ldcv [-h] [-f] [-j] [--cache CACHE] [-c CONFIG]
+               [--color {always,auto,never}]
+               [words [words ...]]
 
    LongMan Console Version
 
@@ -22,10 +23,14 @@ Usage
      -h, --help            show this help message and exit
      -f, --full            print verbose explanations. Default to print first
                            three explanations
+     -j, --json            dump the explanation with JSON style
+     --cache CACHE         specify a word list file then cache words in it to
+                           <cachefile>
+     -c CONFIG, --config CONFIG
+                           specify a config file
      --color {always,auto,never}
                            colorize the output. Default to "auto" or can be
                            "never" or "always"
-     -j, --json            dump the explanation with JSON style
 
 
 Installation

doc/ldcvrc

@@ -0,0 +1,16 @@
+[main]
+# show verbose explanations?
+#full = false
+
+[cache]
+# the file to cache the explanation of word
+# only support environment $HOME which means the user's home directory
+#dbpath = $HOME/.cache/ldcv/ldcv-cache.db3
+
+# the maximum threads to concurrently cache words from list file,
+# but be care of that the server ban you IP
+#threads-max = 20
+
+[net]
+# the maximum time to query a word, second
+#timeout = 7